1. Field of the Invention
The present invention relates to a biosensor using a nanodot and a method of manufacturing the same, and more particularly, to a biosensor capable of providing good sensitivity at a low cost, and a method of manufacturing the same.
This work was supported by the IT R&D program of MIC/IITA[2006-S-007-02, Ubiquitous Health Monitoring Module and System Development].
2. Discussion of Related Art
In general, a biosensor is a device for measuring variation depending on biochemical, optical, thermal, or electrical reaction. The latest tendency in research has been toward research on an electrochemical biosensor.
The electrochemical biosensor senses variation of conductivity generated from a reaction between a target molecule and a probe molecule in a silicon nanowire to detect a specific biomaterial. A structure and an operation of the electrochemical biosensor will be described in detail with reference to FIG. 1.
FIG. 1 is a view showing the structure and operation of a conventional electrochemical biosensor.
Referring to FIG. 1, the conventional electrochemical biosensor 100 includes a semiconductor substrate 110, a source S and a drain D formed on the semiconductor substrate 110, and a straight silicon nanowire 150 disposed between the source S and the drain D. The silicon nanowire 150 is insulated from the semiconductor substrate 110 by an insulating layer 120, and probe molecules P are fixed to a surface of the silicon nanowire 150. When target molecules T are injected through a fluid pipe (not shown), the target molecules T react with the probe molecules P to vary an electric field of the silicon nanowire 150. Therefore, electric potential of the surface of the silicon nanowire 150 is varied to change conductivity of the silicon nanowire 150. By observing the variation of the conductivity in real time, it is possible to detect the target molecules T.
In the conventional electrochemical biosensor, detection sensitivity is in reverse proportion to the width of the silicon nanowire 150, to which the probe molecules 40 are fixed. In recent times, the silicon nanowire has been formed in a bottom-up type or top-down type, which have the following disadvantages, respectively.
First, in the bottom-up type, carbon nanotubes grown through a chemical vapor deposition (CVD) method or silicon nanowires formed through a vapor-liquid solid (VLS) growth method are aligned to a specific position to manufacture a biosensor.
While the silicon nanowires formed through the bottom-up type have very good electrical characteristics, the silicon nanowires must be aligned using an electrophoresis method or fluid flow through a fluid channel in order to align the silicon nanowires at a desired position, making it difficult to control the position when the silicon nanowires are aligned.
On the other hand, in the top-down type, the silicon nanowires are formed through a patterning and etching process using CMOS process technology.
However, since electrical characteristics of the silicon nanowires formed through the top-down type are worse in comparison with the nanowires formed through the bottom-up type, fine patterning technology (electron beam lithography) with nano accuracy must be used, increasing manufacturing cost.
That is, in order to commercialize the biosensor, it must be possible to provide good sensitivity and be manufactured at a low cost.